Nikon 20mm f/1.8G ED Aperture Series: Glacial Erratics in Blue Skylight, Westering Sunstar
Get Nikon 20mm f/1.8 at B&H Photo.
In my review of the Nikon 20/1.8G in DAP is this aperture series at f/1.8, f/2, ... f/11, f/13, f/16 which shows sunstar behavior over the series and is also excellent instruction in flare , contrast and sharpness, color and overall visual impact.
Aperture Series: Glacial Erratics in Blue Skylight, Westering Sunstar (D810)
Includes the f/1.8 - f/16 aperture range in HD and UltraHD sizes in color and black and white, as well as large crops across that full range.